Sub filter safety medium



Jan. l5, 1963 w. F. GAYRING 3,073,452

SUB FILTER SAFETY MEDIUM Filed Feb. 25, 1957 2 Sheets-Shea?l 1 l @nu O I 1(0) n* o l a l "d Ell-o I il i; \S, TIL- 2| INVENTOR. WALLACE. E GAYRNG ATTORN EY Jan. 15, 1963 w. F. GAYRING sUB FILTER SAFETY MEDIUM 2 Sheets-Sheet 2 Filed Feb. 25, 1957 W.V R.l mm Y IFLV M O MUT A T L A M WW renewing incapacita Vcompanying{drawing infwhichif-- v` l A. y FIGURE lifshows fa plan view `of ',a\dry cleaning SUB FILTER SAFETY MEDIUM Wallace F. Gayring, Minoa, N.Y., assigner to Ward Industries Corporation, South Portland, Maine, a corporation of Delaware Filed Feb. 25, 1957, Ser. No. 641,989 3 Claims. n (Cl. Zul-103) This invention relates to the operation of a dry cleaning machine or apparatus, andthe apparatus for reclaiming the solvent for re-use.

The usual dry cleaning process involves the agitation of the materials to be cleaned in a cleaning solvent, such -as trichloroethylene, perchlorethylene orl like `solvents well known in the art, and the extraction ofthe 'solvent from a washer tank, pumped through pipes through Athe tank and is pumped -through the filters for final'condiv tioning of solvent re-use, and returned back to the sump tank. Although the filtration of the cleaning solvent must be repeatedl periodically, it will of course beV understood, that the amount of cleaning which is accomplished, determines the frequency of such an operation. j

Heretofore, various types of vfiltering devices and various typesof filters have been `ernr'iloyed for reclaiming the cleaning solvent. The filters used, as a general rule,

' Uniti@ States datent of have beenl apla-te or bag-type provided with removable lfilter elements formed of suitable material, which from necessity, have to be cleaned. This results in a substantial loss of cleaning solvent, for when the filter is opened, the accumulated dirt and sludge upon the filter elements are' saturated with cleaning uid. Further, the dirt removed from the filter elements has a tendency lto form slime etc. which, in time, would tend to clogthe filter and thus slow the filtering operation. Filter aids have 'there'-v fore been used, such as diatomaceous earth, o r finely divided cellular silica of low specific gravity, such as-dis closed in PatentA No. 1,704,604,`which aid in causing the dirt toform a` porous mass on the filter which does not hinder the passage. of the cleaningsolvent-through the filter. Further means have been provided for cleaning the filter by providing aback-Wash operation into the sub-filter to separate the sludge from the solvent. However, there is a possibili-ty of a ruptured -bag in the sub'- Vfilter or leaking of sludge and dirt Aaround worn or damaged gaskets.

This, in turn, could produce plugging of .the main filter bagsfduring theback'wash operation by ICC filter, sub-lter andsump tank. The dotted line indicates the position of thev filter medium with respect to the sub-filter in the process of reclaiming the cleaning solvent.

FIGURE 2 is an enlarged view of a cross-section of the sub-filter illustrating one embodiment of the present invention. 2 l

FIGURE 3 is a cross-section view of a modification `of i the invention showing a tube connected in the sub-filtertk outlet whereby any sludge-laden solvent will be caught by the bag located in the tube. f

' In order to realize the values and advantages ofthe present invention, -it should be understood that-after `the completion of the Vwashing eycle,'the cleaningfsolvent `is extracted from vthe lgarments by'suitable meanssuch as` extraction. During the washing operation, the solvent'is pumped through a suitable pipe arrangement into a filter' containing filter tubes or other filtering means; The filtered solvent, after passing through the fil-ter flows back into the machine in a clean condition.V When it becomes necessary to clean the filter, the solvent is pumped in a reverse direction through the Vfilter and through a subfilter to reclaim the solvent. .As well known to those familiar in the art, very often during the reclaiming process, the sub-filter containing a filter bag or the like, may,

'rupture due-to an overload of sludge which builds upf v pressure therein. As a result, the loosened sludge and dirt is pumped intol the sump tank. v

In the present invention, with-particular referencev to FIGURE/l of the drawings, whenthe washing-cycle ha's been completed, the cleaning'solvent' is vremoved from the wash tank 10,'by suitable means such'as a pump 50 and" transferred through pipe 11 having avalve' arrangement, in through pipe 12 entering thefiltcringuni which 'is P designated asv a whole by the yreference vcharacter 13.

Located within `the filter 13 are. filter tubes 14, or an'yj other conventional filtering elements used for filtering` the solvent, such as screens etc. As the cleaning solvent passes through these fil-ter tubes 14,'the dirt and sludge carriedinthe cleaning solvent becomes -entrained on the "filter Vtubes 14 together with a filter aid, as is general practice in filters used with dry cleaning solvents;

. to remove.,the'solvent-ladenisludge therefrom. ffI'his is'v pumping Vthe sludge into the sump or storage tanks and finally back into'the main "filter bags. ,y I v This invention has for its objects the provision of a filter medium Vwhich is located with respect to the `outlet of a sub-filter.r This filter medium prevents solvent-laden sludge, which may have inadvertently leaked past adam- This filter medium,when fitted inthe bottom vofthe 4 sludgeV or dirtj'from passing through' the outlet.

A"further object'of this present invention isto` provide*k ",'rneans toA automaticallycut off theuflowffjof solve ludge'fvyhena filtenghagruptures or seal'fvailur'le 4ocpur's.

Fu her objects-of;

aken inconnection;l with chine' comprising the usual washer-whe @ta k sub-filter'outlet, or intheoutletcon'duit will preventany may "b'e 'ini the n v ,portion of the' container ilbetweenthef .,u'yand ali accomplished by- 'a back-Wash operation whereby;'i'asi illustrated in FIGURE l, ythefsolv'ent is pumped-1in al reversed; direction. back through the main filter-llintof the s'ubvfilteri':l'throughxpipeil. f'Ihus, bythe reverse" ilow'of the solvent passing back through'lthe mainffilterlinto the sub`filter. 15, th'e sludge entrained Iin the main filter 13 duringthe filtering operations isy dislodged from the filter elements 14, and'ffpassednto the- 'subfilterlf'15, Whichreceives the solventvladen sludgeand furtherffilters Y the solvent before it returns to the sump tank 30 for re- 2 usein the washer tank 10. f With specificjreference now being 'triade toFIGURES l :and 2 of the'A drawings, lthe-present inventiori'ernbodies or' past amagedysealspinrthens revents,y the'V flow of "sludge l1e`reiiffillu'stratedast l rain mV ofaffscreenaz p sub1-filterv bag l 3 formed of metal. As the cleaning solvent passesfrom the main filter 13 into the sub-filter 15 during the backwash operation, the solvent-laden sludge passes through the sub-filter bag 20 along with the solvent being pumped back into the sump tank 30. Thus it is seen that with the use of this safety metal screen 21, any sludge or matter which has not been entrained in the sub-filter bag 20, or which sludge may have passed through a damaged gasket, is -further filtered in a restricted area, such as at the position of the metal screen 21With respect to the outlet or opening 22. This prevents lthe free flow of the solvent-laden sludge through the conduit 23 which connects the sub-filter 15 -to the sump tank 30. The `safety filter medium 21 t'nus reduces the plugging of the tubes to a minimum. As a furtherprecaution, also located in `the chamber of the sub-tilter 15 is a pressuresensitive means, such as a pressure switch'42, which actuates responsive to a pressure build-up of sludge in the sub-filter 15. As the safety filter medium 21 restricts the flow of he solvent-laden sludge through opening 22 in the case of a ruptured sub-filter bag 20, and as the entrained sludge and dirt build up, the pressure switch 42, v

responsive to this build up, automatically stops the pump flow of tbe solvent, whereupon further passage ofthe solvent is halted. A drain outlet 6G may be provided,` as illustrated in FIGURE 2, connected to the sub-filter 15, whereby upon theY stopping of the flow of the solvent, the solvent-laden sludge may be drained from within the sub-filter -15. Thus it is seen,'that in the case of a ruptured sub-filter bagY 20, the automatiepressure switch 42 prevents the back flow of sludge through a ruptured sublter bag or past a damaged gasket 17 in the subfilter 15 back into vthe main filter 13, or on to the sump tank 30. It is thus seen, that itis possible to replace the ruptured sub-filter bag 20 orfdarnaged gasketg17 without recleaning the entire mainlter 13 and lter elements 14, or without having to refilter the solvent that has passed to-tbe sump tank with sludge entrained therein. A

Another modification of the present invention is` illustrated in FIGURE 3 and comprises an open end tube 40.1which is adapted to be connected to a sub-filter 15.' As illustrated in FIGURE `3, this tube- 40 is connected to a sub-filter` outlet 2x3 and has located therein asafety filter medium, such as a strainer 41 or bag 41 which catches and further filters the solvent-laden sludge passing through the sub-filter 15 during the back wash operation. .n

A t pressure responsive switch 42 is suitably attached'to the tube 40. In the case of a ruptured sub-filter bag 26 or damaged `gasket 17the` free ow of the sludge-laden' 42, responsive; to this build up, automatically' shuts 01T the :pump flow of the solvent to the sump `tank 30 and t prevents the backflow of the sludge-ladensolvent into cleaned, as hereinabove described, eliminating the corn plete removal of the solvent from the system, as well as the complete removal of the filter elements 14 in the main lter 13. It is also seen, that any matter which may not have been filtered in the sub-filter 15 during the back wash operation is further filtered through the safety filter medium 41 -in tube 40, before the solvent returns through the connecting pipes into the sump tank 30 -for re-use in the washer wheel tank 10.

The size screen mesh for screen 21 is selected laccordingly with engineering practices known to those skilled inthe art.

It is seen from the above disclosure, that during the reclaiming of the cleaning solvent, viz. the passage of` the -solvent in a reverse ow during the back wash op-` eration' from the main filter 13 in through the subdilter 15, the reclaiming process is increased in efliciency by the use of the safety filter medium located either within the lsub-filter 15, or a tube as disclosed. The use of this safety filter medium acts as a preventative measure against any sludge entering the sump tank 30 during the back wash operation in the event a filter bag 20 in the subfi1ter 15 should rupture, and reduces the chances of ,outlets and pipes from becoming plugged. The use of the automatic pressure-sensitive means prevents the back flow of sludgeinto the main filter 13.

-While a specific form of the invention in the improvement of the reclaiming of the cleaning solvent during the back wash operation has been described and ,illus-` trated herein, it is desired to -be understood that the same may be varied, within the scope of `the appended claims, without departing from the spirit of the invention.

What is claimed is: t

l. In a cleaning machine having a main filter,` a sub-` filter connectedV with the main filter, and a pump for` transferring solvent from the main lilterto the sub-lter during the back wash operation, said subdilter including a housing having filter means therein, an outlet extending from said housing, a filter medium mounted in said outlet whereby the outowing solvent is further Vfiltered.

therethrough during theback wash operation, and a pressure sensitive means connected to said housing and responsive to a pressure build-up between the filter means. and the filter medium for stopping the pump. t `2. In a cleaningmachineas defined in claim l, said lter medium comprising a metal screen.

l 3. In a cleaning machine as defined in claim 2,tsaid pressure sensitive means constituting a pressure switch.

. McCoy Ian. 3, l1956 

1. IN A CLEANING MACHINE HAVING A MAIN FILTER, A SUBFILTER CONNECTED WITH THE MAIN FILTER, AND A PUMP FOR TRANSFERRING SOLVENT FROM THE MAIN FILTER TO THE SUB-FILTER DURING THE BACK WASH OPERATION, SAID SUB-FILTER INCLUDING A HOUSING HAVING FILTER MEANS THEREIN, AN OUTLET EXTENDING FROM SAID HOUSING, A FILTER MEDIUM MOUNTED IN SAID OUTLET WHEREBY THE OUTFLOWING SOLVENT IS FURTHER FILTERED THERTHROUGH DURING THE BACK WASH OPERATION, AND A PRESSURE SENSITIVE MEANS CONNECTED TO SAID HOUSING AND RESPONSIVE TO A PRESSURE BUILD-UP BETWEEN THE FILTER MEANS AND THE FILTER MEDIUM FOR STOPPING THE PUMP. 